In manufacturing a nonvolatile semiconductor memory device such as a NAND flash memory, a tunnel insulating film and a charge storage film for forming floating gate electrodes are formed on a semiconductor substrate. Then, grooves for element isolation are formed on the semiconductor substrate to isolate between adjacent active areas with insulation. By forming the grooves, laminated patterns including portions of the semiconductor substrate, the tunnel insulating film and the charge storage film are formed. Subsequently, a rinsing process is performed. In the rinsing process, the laminated patterns may be collapsed during drying of a rinsing solution.
In recent years, with the miniaturization of patterns, variation easily occurs in the dimension of width of the grooves formed for insulating isolation, i.e., the intervals between adjacent active areas. As a result, variation in the dimension of depth of the grooves also easily occurs, and the above-described laminated patterns are easily collapsed.
As a technique for suppressing collapse of the laminated patterns, a technique of solidification drying is known. In this technique, after the semiconductor substrate is rinsed by a rinsing solution, grooves between adjacent laminated patterns are filled with a solution in which a sublimation substance is dissolved, and the sublimation substance is changed directly from a solid state to a gas state without passing through a liquid state. According to this technique, since surface tension caused by the rinsing solution can be prevented from being exerted on the laminated patterns, it is possible to suppress collapse of the laminated patterns during a drying process.
However, a film-formability of the sublimation substance for the laminated patterns cannot be sufficient depending on the kind of the material constituting the laminated patterns. In such a case, the sublimation substance is not formed well between the adjacent laminated patterns, and the effect of suppressing collapse of the laminated patterns is not obtained sufficiently.